This invention relates to vehicles for topical or local application of corticosteroids and to mixtures of the vehicle and medicaments. In particular, this invention relates to new, improved medicament vehicles having advantages over previously known vehicles.
One of the oldest types of medicament vehicles is the ointment, a preparation containing active medications that can be readily applied and rubbed into the skin. It serves as a means for distributing the medication uniformly over the skin surface and maintaining it there until beneficial action can occur. The earliest ointment preparations were based on fats, waxes, greases and petrolatum. These are, by nature, greasy or not water-washable and have a limited ability to release medication to the skin. A non-aqueous ointment of more recent origin is a mixture of polyethylene glycols having molecular weights of 1,000 to 20,000. This vehicle, although water-washable, has a greasy texture and does not provide an occlusive dressing on a treated surface.
Topical corticosteroid formulations are extensively employed in the treatment of skin disorders, such as dermatitis. To be therapeutically effective, the active ingredient must be in a molecular dispersion to facilitate desired percutaneous absorption which is particularly important is achieving a therapeutic response for the management of psoriasis. Unfortunately, the more effective corticosteroids are essentially insoluble in water (less than 0.0005% soluble), hydrocarbon vehicles such as mineral oil, petrolatum, and polyethylene gelled mineral oil. Various organic solvents and solubilizers have been found to be good solvents for such steroid. However, they have been found to be unsuitable for commercial application for reasons such as their high volatility and low boiling points, their disagreeable odor, their "paint removing" property, and their undesirable skin reaction. Furthermore, various water-soluble emulsifiers and oily liquids or emollients have been suggested for use in preparing creams or lotions. However, because of the undesirably low solubility of the corticosteroid in such vehicles, higher levels of these materials in topical products are required thereby increasing their cost, increasing the risk of irritation and also adversely affecting their cosmetic elegance.
By local application it is meant use in body cavities including mucous membranes, i.e., vaginal, nasal, anal, etc. and in the treatment of inflammation and irritations which occur, including vaginitis, hemorrhoids and the like. Accordingly, in view of the above considerations, it is seen that a need exists for a suitable vehicle capable of solubilizing a sufficient amount of the corticosteroid so that it may be employed in topical or local formulations, while being dermatologically beneficial, stable, and pharmaceutically acceptable.
It is accordingly the purpose of this invention to provide an essentially water-washable base which provides an occlusive film for longer and better therapeutical activity; release the medicaments more quickly and effectively; bring dissolved therapeutic agent in known dilution in contact with the skin; spread evenly and adhere well even if the skin is moist; be readily removed from the skin or fabrics with water; serve as an excellent levigating material for many prescribed ingredients that usually require separate treatment before being incorporated into one of the bases; and because it does not hydrolyze, deteriorate, become rancid, support mold growth or require preservatives.
It is a further object of this invention to provide a vehicle using a unique system, new for topical or local preparations, which has exceptional solubilizing properties particularly for corticosteroids.
It is a still further object of the present invention to provide a new topical or local preparation which can produce a foam when packaged either in the form of an aerosol or a non-aerosol foam-forming closure system.